The Key Technologies Of Full Services Access Based On PON Structure

With the development of multimedia technology,communications technology and hardware storage technology,People's demand for network bandwidth showsing explosive growth,increase the increased amount of information makes the bandwidth to become a serious bottleneck,forcing the network to a higher speed,people no longer satisfy with the previous single,passive way to obtain information,but to actively participate in programs.VOD(Video on Demand,VOD) is an interactive services, cable television field and communications field pay more attention to this field. However,in the field of access network,the traditional cable TV network currently uses optical fiber / coaxial cable hybrid network(HFC) to achieve two-way transformation.At present,two-way transformation of HFC has a variety of technologies,the main method adopt the way of two-way HFC + Cable Modern,that is, the original low-end frequency of CATV system uses as return channel to achieve non-symmetric transmission,this manner has some shortcomings,such as limited available bandwidth and the "flannel effect"of HFC return channel..And the side of telecommunications currently adopt the access technology of ADSL,because of the limits of bandwidth and transmission distance,it isthey are both hard to have long-term development.So either in terms of radio and television or from the telecommunications area, Faced with the problem of bandwidth bottleneck,people generally consider the Fiber AccessFiber to the Home(FTTH) as a next-generation access solutions of transmission network,in the realization solutions of Fiber AccessFTTH,EPON and GEPON used as the main direction of development.(EPON,Ethernet Passive Optical Network) used as method of multi-service broadband access has excellent characteristics,people generally consider EPON / GEPON technology as access solution to achieve "triple play","triple-play".EPON combines both the advantages PON technology and Ethernet technology: low cost;high-bandwidth;strong expansibility,and flexible and rapid restructuring of the service;compatibility with existing Ethernet;convenient management and so on. However,EPON using unicast or multicast is hard to achieve large-capacity transmission of video signals,it is difficult to achieve the system's expansion of video services,thus affect the access of whole business.And subcarrier multiplexing can achieve high-capacity broadband optical communication.Therefore,this paper,two types of SCM and EPON technology,using wavelength division multiplexing(WDM) technology werecarried on the different wavelengths.Using1550nm bring down the DVB standard signal,the digital video signal encoded as H.264 video streams,and then using QAM modulate carrier wave,the last was modulated on optical carrier using SCM technology.By means of the WDM,SCM and EPON effective integration of various technologies,the program based on the existing EPON standard achieves gradual expansion,and holds the most simplified optical path,has the feasibility and superiority.In this way,they can transmit large capacity of video signal,the changes on the network is also very small,very convenient and can easily access a variety of interactive multimedia services.On this base of technology,this paper proposes a bandwidth allocation algorithm,on the distribution project which combine unicast and broadcast,analyse the system performance via software,based on SCM / Ethernet PON,make use of two kinds of Video-On-Demand which are NVOD and VOD,and the advantage of two kinds of video-on-demand business which are DVB and IPTV, improve the largest number of concurrent video-on-demand which the network system supports by a certain algorithm,reduce the average waiting time,minimize bandwidth resources,provide video-on-demand services for a large number of users. Combines the advantage of the merits of two types of technology carrying video. Through the rational allocation of bandwidth maximize the use of bandwidth resources, provide users with higher bandwidth.Finally,With the Method of the scheduling of the bandwidth,provide better services to users.Finally this paper,in the conditions of FTTH access,we bring forward an design of integrated access gateway,it can realizes the integrated access of VoIP voice service, internet data services and video services.PAS6301 chip achieves the control of voice, video and data services.The project achieves the data services via Ethernet transceiver, realizes VoIP services in conjunction with the DSP which have voice compression processing functions;With the collaboration of AVIA9700-QCK and FH8601,the two chips can deal with two kinds of video signals encoded by MPEG-2 and H.264. Especially on the aspect of the video business,the system combines the advantages of IPTV and the DVB to offer a platform for receiving two signals,allows users to use an ordinary television which can both watch there content-rich resources of high-definition digital TV programs encoded by MPEG-2 and watch time-lapse and interactive IPTV video programs encoded by H.264.It meets the needs of users requirements of watch high-definition and interactive television program.In the conditions of EPON,it achieves the broadcasts of high-definition programs,along with the access and return of data,voice and other business-wide.Through the simulation analysis,we focuses on the two encoding mode on the impact of bandwidth consumption and make analyse and comparison through simulation.we can intuitively see the advantages of H.264 video coding in the video-on-demand business.On the perspective of benefits and technique,video-on-demand system based on H.264,will be the development trend of the VOD business.